AGRICULTURAL  EXPERIMENT -STATION  ' 


0.  E.  S  I  tbrahy.  Cop.  2. 


CONNECTICUT 


NEW     HAVEN,    CONN 


BULLETIN    151,   JUNE,   1905. 


ENTOMOLOGICAL    SERIES,    No.    12. 


The   Chief   Injurious   Scale-lnsecte   of 
Connecticut. 


Rose  scale  :  twice  enlarged. 

CONTENTS.  page 

Officers  and  Staff  of  Station 2 

Chief  Injurious  Scale-Insects  of  Connecticut 3 


Unarmored  or  soft  scales  :  PAGE 

Greenhouse  Orthezia 4 

Pit-making  oak  scale 4 

Elm  scale 5 

Woolly  maple  leaf  scale 5 

Common  mealy  bug 6 

Long  spined  mealy  bug 6 

Cottony  maple  scale 6 

Soft  scale 7 

Apricot  scale 8 

New  York  plum  scale 8 

Terrapin  scale 8 

Tulip  scale q 

Hemispherical  scale n 


Armored  scales  :  page 

White  elm  scale 10 

Euonymus  scale 10 

Scurfy  scale 11 

Pine  leaf  scale n 

Rose  scale ir 

Putnam's  scale 12 

Cherry  scale 12 

White  or  oleander  scale 12 

European  fruit  scale 13 

San  Jose  scale 13 

Elm  Aspidiotus 14 

Circular  or  fig  scale 14 

•  Morgan's  scale 15 

Oyster  shell  scale 15 

Thread  scale   16 

Chaff  scale 16 


The  Bulletins  of  this  Station  are  mailed  free  to  citizens  of  Connec- 
ticut who  apply  for  them,  and  to  others  as  far  as  the  limited  editions 
permit. 


CONNECTICUT  AGRICULTURAL  EXPERIMENT  STATION. 

OFFICEES    .A-IST-D     STAFF. 


BOARD    OF    CONTROL. 

His  Excellency,  Henry  Roberts,  Ex  officio,,  President. 

Prof.  W.  O.  Atwater  Middletown. 

Prof.  W.  H.  Brewer,  Secretary  New  Haven. 

B.  W.  Collins  Meriden. 

T.  S.  Gold West  Cornwall. 

Edwin  Hoyt   New  Canaan. 

J.  H.  Webb   Hamden. 

E.  H.  Jenkins,  Director  and  Treasurer New  Haven. 


STATION    STAFF. 

Chemists. 

Analytical  Laboratory. 

A.  L.  Winton,  Ph.D.,  Chemist  in  charge. 

E.  Monroe  Bailey,  Ph.B.  I.  A.  Andrew,  Ph.B. 

Kate  G.  Barber,  B.S. 

Laboratory  for  the  Study  of  Proteids. 
T.  B.  Osborne,  Ph.D.,  Chemist  in  charge.  I.  F.  Harris,  M.S. 

Botanist. 
G.  P.  Clinton,  S.D. 

Entomologist. 
W.  E.  Britton,  Ph.D. 

Assistant  to  the  Entomologist. 
B.  H.  Walden,  BAgr. 

Forester. 
Austin  F.  Hawes,  M.F. 

Grass  Gardener. 
James  B.  Olcott,  South  Manchester. 

Stenographers  and  Clerks. 

Miss  V.  E.  Cole. 
Miss  L.  M.  Brautlecht. 

In  charge  of  Buildings  and  Grounds. 
William  Veitch. 

Laboratory  Helper. 
Hugo  Lange. 

Sampling  Agent. 
V.  L.  Churchill,  New  Haven. 


The   Chief   Injurious  Scale-Insects   of 
Connecticut. 


By  W.  E.  Britton. 


The  terms  "scale,"  "scale-insect''  and  "bark-louse"  are  com- 
monly used  to  designate  insects  belonging  to  the  family  Coccidae 
of  the  order  Homoptera.  The  Homoptera  are  often  included 
in  the  Hemiptera,  to  which  belong  the  true  bugs,  aphids  or 
plant-lice,  and  leaf-hoppers.  These  insects  all  suck  their  food, 
and  many  of  them  cause  serious  injury  to  cultivated  plants. 
The  Hemiptera  have  incomplete  transformations,  and  the 
Coccidae  are  probably  the  most  degraded  of  the  Hemiptera. 
The  males  are  said  to  have  complete  transformations,  but  pos- 
sess only  two  wings  in  the  adult  state.  Soon  after  birth  the 
young  crawl  about  for  a  few  hours ;  otherwise  the  females  are 
without  means  of  locomotion  except  in  a  few  species,  and  are 
attached  to  the  bark  or  foliage  of  trees  and  plants,  from  which 
they  suck  out  the  sap  for  food.  Some  of  our  worst  pests  are 
scale-insects.  The  object  of  this  bulletin  is  to  illustrate  and 
describe  briefly  the  more  important  kinds  occurring  in  Con- 
necticut, so  that  people  will  be  able  to  recognize  them  more 
readily  and  combat  them  more  successfully. 

As  some  of  these  insects  secrete  a  substance  which  forms  a 
shell  or  covering  for  protection,  they  are  called  armored  scales. 
Other  kinds  not  forming  shells  are  known  as  unarmored  or  soft 
scales.  Most  of  the  unarmored  scales  secrete  honey  dew  like 
the  plant-lice. 

The  Latin  names  and  arrangement  of  the  following  species 
are  the  same  as  given  in  Mrs.  Fernald's  Catalogue  of  the 
Coccidae  of  the  World.  The  illustrations  are  all  original,  and 
show  the  insects  natural  size  except  where  otherwise  indicated. 
Figure  5  is  from  a  drawing.     All  others  are  from  photographs. 


CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    151. 


UNARMORED  OR  SOFT  SCALES. 


1.  THE  GREENHOUSE  ORTHEZIA.— Orthesia  insignis  Dougl. 

This  insect  is  not  fixed, 
but  crawls  about  like  the 
mealy  bugs,  and  is  shown 
in  Figure  I.  Full-grown 
specimens  are  about  1.5  mm 
long.  It  attacks  a  great 
variety  of  greenhouse 
plants,  Lantana  and  Coleus 
being  favorites.  The  treat- 
ment used  against  mealy 
bugs  is  advised  against  this 
insect.  All  breed  continu- 
ously in  greenhouses,  and 

,^  .,     .  there   are    probably    many 

Fig.    1.     The    greenhouse    Orthezia    on  c  J  .  J 

Lantana  leaf.     Twice  natural  size.  generations  each  year. 


2.  PIT-MAKING  OAK  SCALE- 

Asterolecanium  variolosum 
Ratz. 


This  scale  is  circular,  usually  greenish- 
yellow  in  color,  and  has  a  glassy  appear- 
ance. It  forms  a  pit  or  depression  in 
the  bark  where  it  is  situated,  and  it  is 
about  2  mm  in  diameter.  (See  Figure 
2.)  This  species  has  been  sent  to  the 
Station  several  times  on  English  oak, 
Quercus  robtir,  though  it  is  known  to 
attack  other  oaks.  Kerosene  emulsion 
and  whale  oil  soap  have  been  used  as  a 
spray  with  good  results  in  destroying 
this  insect. 


Fig.   2. 
Pit-making  oak  scale. 


UNARMORED    SCALES. 


3.  ELM  SCALE — Gossyparia  spuria  Modeer. 

A  dark-colored  oval  scale  margined  by  a  white  cottony 
fringe  is  not  uncommon  upon  elm  trees  about  New  Haven. 
It  seems  to  prefer  small  trees, 
but  is  sometimes  found  on  the 
lower  branches  of  medium 
sized  and  large  trees.  The 
insect  is  about  3  mm  long, 
brown  or  black  surrounded 
by  a  fringe  of  white  wax,  and 
is  shown  in  Figure  3.  The 
young  are  born  alive,  appear- 
ing about  the  middle  of  June 
in  Connecticut,  and  settle 
along  the  veins  of  the  leaves 
chiefly  on  the  under  sides. 
Later  in  the  season  they  re- 
turn to  the  larger  branches 
and  trunk,  and  occupy  the 
crevices  of  the  bark,  where 
they  remain  through  the  win- 
ter. There  is  but  one  brood 
each  year.  Honey  dew  is 
given  off  profusely  by  the  nearly  mature  females,  and  often 
drips  upon  the  ground.  The  scales  are  readily  destroyed  at 
any  time  of  the  year  by  spraying  with  kerosene  emulsion  or 
soap  and  water. 

4.  WOOLLY    MAPLE    LEAF    SCALE  —  Phenacoccus    acericola 

King. 
White  powdery  masses  of  wax  6  or  7  mm  long  are  frequently 
seen  on  the  under  sides  of  leaves  of  the  sugar  maple.  The 
waxy  mass  contains  the  mature  female  (often  dead)  and  a  large 
number  of  eggs.  The  young  remain  on  the  leaves  until  winter 
approaches,  when  they  go  into  the  crevices  of  the  rough  bark  of 
the  trunk  and  larger  limbs,  where  they  make  a  sort  of  nest  by 
lining  the  crevices  with  wax.  They  remain  here  until  May. 
The  white  oval  cocoons  of  the  males  are  often  abundant  on  the 
bark.  There  are  three  generations  each  year.  The  insect  has 
been  collected  at  New  Haven  and  South  Norwalk,  but  doubt- 
less occurs  elsewhere  in  the  state.  Very  little  seems  to  be 
known  about  remedies  for  this  insect,  but  probably  kerosene 
emulsion  will  prove  effective. 


Fig.  3.     Elm  scale. 


CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    151. 


5.  COMMON  MEALY  BUG— Pseudoco ecus  citri  Risso. 

The  mealy  bug-  is  a  common  pest  of  plants  in  greenhouses 
and   dwellings   and   even  out   of    doors    in    summer.     Unlike 

most  scales,  the  mealy  bugs 
are  not  fixed  to  their  food 
plants,  but  are  able  to  move 
about,  and  they  attack  nearly 
all  kinds  of  plants.  The  full- 
grown  females  are  about  4  mm 
long  and  oval  in  shape.  They 
are  creamy  or  dirty  white, 
and  covered  with  a  wax  secre- 
tion which  gives  them  a  mealy 
appearance.  They  usually 
congregate  in  the  crotches 
and  at  the  axils  of  the  leaves 
so  as  to  be  somewhat  pro- 
tected. The  illustration,  Fig- 
ure 4,  shows  them  gathered 
along  the  mid-vein  of  a  leaf. 
Spraying  with  soap  and  water 
or  fir  tree  oil  or  dipping  the 
plants  in  the  mixture  is  the 
remedy,  but  hydrocyanic  acid 
gas  fumigation  is  doubtless 
the  most  satisfactory  for  greenhouses. 


Fig.  4. 


Common  mealy  bug  on 
oleander. 


6.  LONG  SPINED  MEALY  BTJG  —  Pseudococcus  longispinus 

Targ. 

Resembles   the  preceding,   except  that  the  adults  bear   fila- 
mentous appendages  at  the  posterior  end  of  the  body.      The 

species  is  well  distributed. 


7.  COTTONY  MAPLE  SCALE— Pulvinaria  innumerabilis  Rathv. 

This  scale  can  be  recognized  during  early  summer  by  the 
large  white  egg-masses  on  the  twigs.  Nearly  all  maples  as 
well  as  many  other  trees  are  attacked,  but  the  insect  seems  to 
prefer  the  silver  maple.     It  is  not  as  yet  a  very  serious  pest  in 


UNARMORED    SCALES. 


>** 


Connecticut,  but  in  Chicago,  Denver,  and  some  other  Western 
cities  the  maples  are  being  seriously  injured  by  it,  and  extensive 
spraying  is  practiced.  There  is  one  annual  brood,  with  eggs 
laid  in  May  and  June  which  hatch  in  July  and  August.  The 
young  first  settle  on  the  leaves.     The  ;: 

males  appear  in  early  fall  and  mate 
with  the  females,  which  migrate  to 
the  twigs,  where  they  remain  through 
the  winter.  In  the  spring  they  in- 
crease rapidly  in  size,  and  soon 
deposit  their  egg-masses  and  shrivel 
and  die.  The  brown  female  with 
white  egg-mass  protruding  posteri- 
orly is  about  12  mm  {%  inch)  long, 
and  is  shown  in  Figure  5.  The 
species  is  abundantly  attacked  by 
insect  parasites. 

Kerosene   emulsion   is   used   as   a 
remedy. 

A  closely  allied  species,  P.  aceri- 

cola  Walsh  &  Rilev,  doubtless  occurs   FlG;  5-     Cottony  maple  scale  ; 

females  and  egg-masses. 
here,  but  the  writer  has  not  observed 

it.  It  seems  to  be  confined  almost  exclusively  to  the  silver 
maple,  and  the  egg-masses  are  laid  on  the  leaves  instead  of 
the  twigs.  This  requires  two  migrations, — from  the  leaves  to 
the  twigs  in  fall,  and  from  twigs  to  the  new  leaves  in  spring. 
The  females  with  egg-masses  are  about  /2  inch  long,  the  egg- 
mass  tapering  backward,  with  four  longitudinal  ridges. 


8.  SOFT  SCALE— Coccus  hcsperidum  Linn. 

Much  has  been  written  about  this  scale,  which  was  formerly 
placed  in  the  genus  Lecanium.  It  is  an  oval,  slightly  convex 
brown  species  commonly  found  on  citrus  trees,  oleanders  and 
many  other  plants  in  greenhouses.  Females  are  viviparous,  but 
the  generations  are  not  well  marked.  Soap  and  water  or  kero- 
sene emulsion  will  readily  destroy  these  scales  at  any  season  of 
the  year. 


8 


CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    151. 


9.  APRICOT  SCALE — Eulecanium  armeniacum  Craw. 

During-  recent  years  this  species  has  become  common  out  of 
doors  in  Connecticut,  and  a  wide  range  of  plants  are  attacked. 

We  have  observed  it  on  plum, 
grape,  chestnut,  ash  and  rose.  It 
is  oval  in  shape,  about  4  mm  long, 
strongly  convex,  and  light  or  dark 
brown  in  color.  Figure  6  gives  a 
good  idea  of  its  appearance.  This 
scale  is  sufficiently  abundant  to "? 
cause  considerable  injury,  and 
remedial  measures  must  be  taken 
<j,gainst  ,  it.  There  is  one  brood 
annually,"  the  eggs  hatch  about  July 
1  st,  and  the  scale  winters  in  a  par- 
tially gro^vn  condition.  Spraying 
^Jtn  winter.*  ^itfcr  kerosene  emufteion 
has  been  successful,  but  where  orchards  are  treated  wiffi3*FiMer ; 
and  sulphur  washes  for  the  San  Jose  scale,  no  other  treatment 
need  be  given.  *'- 


Fig.  6.     Apricot  scale  on  plum; 

immature  scales  at  left, 

old  shells  at  right. 


10.  NEW  YORK  PLUM  SCALE  — Eulecanium  cerasifex  Fitch. 

Plum  twigs  thoroughly  infested  with  this 
scale  were  received  from  Berlin  in  1904. 
Superficially  it  looks  like  E.  armeniacum, 
which  is  shown  in  Figure  6.  The  writer 
has  made  no  observations  regarding  its  life 
history.  Where  it  occurs  the  same  treat- 
ment advised  for  armeniacum  should  be 
employed. 


11.  TERRAPIN  SCALE— Eulecanium 
nigrofasciatum  Perg. 

The  writer  has  several  times  collected 
this  scale  from  the  twigs  of  silver  maple, 
though  it  is  known  to  infest  fruit  and  other 
trees.  The  females  are  smaller  than  in  any 
other  species  of  the  genus  mentioned  in 
this  bulletin.  The  adult  female  is  of  a  red- 
dish color  spotted  with  dark  red  or  black, 


Fig.  7.   Terrapin  scale 
on  silver  maple. 


UNARMORED    SCALES.  O 

2  mm  long",  convex,  with  about  twelve  radiating"  ridges,  most 
conspicuous  near  the  margin.  There  is  probably  one  brood 
each  year,  eggs  being  formed  in  May  and  hatching  in  July. 
(See  Figure  7.) 

12.  TULIP  SCALE — Eulecanium  tulipiferae  Cook. 

This  scale  is  becoming  quite  common  on  wild  and  cultivated 

It  is  the  largest  of  all  the 
females  often  reaching  a 
or  I3  of  an  inch.  The 
smaller  and  more  elon- 
grey  pupa  skins  remain 
adult  males  have  emerged, 
shown  in  Figure  8.  Ap- 
one  brood  each  year,  the 


tulip  trees  throughout  the  state. 
brown  scales,  the  hemispherical 
diameter  of  8  mm, 
male  scales  are  much 
gated.  The  light 
on  the  bark  after  the 
Both  sexes  are 
parently  there  is  but 


Fig.  8.     Tulip  scale  on  tulip  tree.     Large  females  are  shown  above, 
and  small  male  shells  on  lower  twig. 

viviparous  females  producing  young  about  September  1st. 
They  are  partially  grown  when  winter  sets  in.  As  a  rule  the 
lower  branches  are  first  attacked,  and  often  killed,  when  those 
next  higher  will  in  turn  become  infested.  Linden  and  magno- 
lia are  also  attacked  by  this  scale.  Kerosene  emulsion,  and 
soap  and  water  applied  in  the  form  of  a  spray,  in  autumn,  are 
the  common  remedies. 


13.  HEMISPHERICAL  SCALE  —  Saissetia  hemispkaerica  Targ. 

This  is  probably  the  most  common  of  all  the  large  brown 
scales  found  in  greenhouses  and  dwellings.  It  has  a  long  list 
of  food  plants,  and  may  be  expected  to  attack  almost  any  kind 


IO  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    151. 


of  plant,  but  chiefly  palms,  ferns,   Cycas  and   orchids.     It  is 
from  3  to  4  mm  long',  and  reddish  or  dark   brown  in  color. 

Specimens 
are  found  on 
both  leaves 
and  stems. 
(See  Figure 
9.)     It  prob- 

fably  breeds 
continuously 
throughout 
the  year. 
Kerosene 
.  emulsion,    fir 

tree  oil  and 
soap  and 
water  can  be 
used  as  sprays 
and  green- 
houses can  be 
fumigated 
with  hydro- 
cyanic acid 
gas  to  destroy 

this  insect. 
Fig.   9.      Hemispherical  scale  on  fern. 

ARMORED   SCALES. 

14.  WHITE  ELM  SCALE— 

Ch ionaspis  americana 
Johnson. 
This  scale  attacks  the  twigs 
of  the  elm,  and  closely  resem- 
bles the  scurfy  scale,  shown 
in  Figure  1 1 .  It  is  not  very 
abundant  in  Connecticut. 

15.  ETJONYMTJS  SCALE— 
Chionaspis  euonymi  Comst. 
This    species    was    recently 

sent  to  the  writer  from  -Hart-  Fig.  io.     Euonymus  scale  on  Euony- 

i^~A     „,u^~~    ;<-    ,,,„„    nU-.^An^t.       mus  radicans.     The  white  shells  are 
lord,  where  it  was  abundant  f          .  ,      ,  ,       , 

'  males.     A  few  larger  grey  females 

on  Euonymus  radicans  along      are  present. 


ARMORED    SCALES. 


a  brick  wall.     The  wall  was  covered  with  canvas,  and  the  plants 
fumigated  with  hydrocyanic  gas. 

The  euonymus  scale  resembles  the  scurfy  scale,  but  the 
females  are  somewhat  smaller  and  darker  in  color.  It  passes 
the  winter  in  the  egg  stage,  and  the  different  species  of  Euony- 
mus and  the  orange  are  attacked.     It  is  shown  in  Figure  10. 

16.  SCURFY  SCALE— Chionaspis  furfnra  Fitch. 

The  female  shell  is  broadly  pyriform, 
3  mm  in  length,  and  white  or  light  grey. 
See  Figure  1 1 .  The  male  is  much  smaller, 
white,  with  sides  parallel,  and  three 
ridges  along  the  back.  A  single  brood 
is  formed  each  year,  and  the  winter  is 
passed  in  the  egg  stage.  These  eggs 
are  oval  in  shape,  purple  in  color,  and 
hatch  between  May  20th  and  June  1st. 
Spraying  with  soap  and  water  or  kero- 
sene emulsion  soon  after  the  eggs  hatch 
will  readily  destroy  the  young.  For  a 
more  complete  history  of  this  insect  the 
reader  is   referred  to    Bulletin   No.    143 

Fig.  11.    Scurfy  scale  on  or  the  Report  of  this  Station  for   1903, 
currant  ;  males  at  left, 
females  at  right.  page  227. 


17.  PINE  LEAP  SCALE— Chionaspis  pinifoliac  Fitch. 

Resembles  the  preceding,  but  is  attached  to 
the  leaves  or  "  needles  "  of  the  pine,  spruce 
and  other  coniferous  trees.  It  has  been  collected 
at  South  Manchester  on  Pinus  mughus.  There 
are  two  broods  each  year,  and  the  winter  is 
passed  in  the  egg  stage.     See  Figure  12. 

18.  ROSE  SCALE— Aulacaspis  rosac  Bouche. 

A  large  white  scale  is  sometimes  seen  on  rose 
bushes,  raspberry  or  blackberry  canes,  especially 
where  growing  in  crowded  rows  or  clumps. 
The  female  is  nearly  circular,  2.5  mm  in  diam- 
eter, and  is  shown  on  the  cover  of  this  bulletin. 
The  male  is  much  smaller,  long  and  narrowr,  with 


Fig.   12. 
Pine  leaf  scale. 
Enlarged  about 

twice. 


12  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    151. 

three  parallel  ridges  running  lengthwise  of  the  shell.  Professor 
John  B.  Smith  of  New  Jersey  has  studied  this  scale  recently, 
and  finds  that  all  stages  from  the  egg  to  the  mature  female 
occur  at  the  same  time  during  the  winter  and  throughout  the 
season.  Probably  there  are  but  three  complete  broods,  but 
these  overlap  so  that  breeding  is  almost  continuous. 

As  all  stages  of  the  insect  occur  at  the  same  time  remedial 
treatment  is  somewhat  difficult,  as  the  eggs  are  usually  not 
killed  by  sprays,  and  sometimes  survive  even  fumigation.  The 
worst  infested  canes  should  be  cut  out  and  burned.  Kerosene 
emulsion  or  soap  and  water  should  be  used  as  a  summer  spray, 
and  the  lime  and  sulphur  mixture  may  be  applied  to  the  dormant 
plants  in  winter. 

19.  PUTNAM'S  SCALE— Aspidiotus  ancylus  Putnam. 

This  is  a  small  circular  scale,  2  mm  in  diameter,  which  occurs 
throughout  the  state  on  fruit  trees,  but  perhaps  most  frequently 
upon  currants,  often  killing  the  second  year  canes  or  shoots. 
The  shells  of  this  scale  are  usually  not  as  nearly  circular  as  the 
San  Jose  scale,  but  it  is  often  difficult  to  distinguish  them  in 
the  field.     Apparently  there  is  but  one  brood  each  year. 

20.  CHERRY  SCALE — Aspidiotus  forbesi  Johnson. 

This  scale  closely  resembles  the  preceding,  and  though  not  so 
widely  distributed,  has  been  found  upon  fruit  trees  in  Con- 
necticut. It  should  be  regarded  as  a  serious  enemy,  and  treated 
in  the  same  way  as  the  San  Jose  scale. 

21.  WHITE  SCALE;   OLEAN- 
DER SCALE— Aspidi- 
otus hederae  Vail. 

This  scale  is  a  pest  of  green- 
houses, where  it  attacks  olean- 
der, croton,  ivy,  palms,  camel- 
lia and  many  other  plants.  It 
is  nearly  circular  in  shape, 
and  white  or  light  grey  in 
color,  making  it  conspicuous 
on  the  green  leaves  and  stems. 
(See  Figure  13.)     It  probably 

t,  W1  ,       ,  ,        breeds  continuously  in  green- 

riG.  13.      White  or  oleander  scale  . 

on  Croton  leaf.  houses.      Fumigating    the 


ARMORED    SCALES.  1 3 

house  with  hydrocyanic  acid  gas,  spraying"  the  infested  plants 
with  either  whale  oil  or  common  soap  (i  lb.  in  8  gallons  of 
water)  are  the  remedies  for  this  scale. 

22.  EUROPEAN  FRUIT  SCALE  —  Aspidiotus  ostraeformis 

Curtis. 

This  scale  is  not  known  to  be  established  in  Connecticut,  but 
will  doubtless  become  so,  as  it  has  been  found  on  nursery  trees 
sent  into  the  state.  It  looks  very  much  like  the  cherry,  Put- 
nam's, and  San  Jose  scales,  and  can  be  distinguished  from 
them  only  by  means  of  the  compound  microscope.  In  fact 
these  four  species  resemble  each  other  so  closely  that  the  fruit 
grower  cannot  distinguish  between  them  unless  he  is  an  ento- 
mologist. The  European  fruit  scale  attacks  all  kinds  of  orchard 
trees,  and  there  is  probably  a  single  brood  each  year. 

23.  SAN"  JOSE  SCALE — Aspidiotus  pemiciosus  Comst. 

This  is  a  circular  scale,  light  or  dark  grey  in  color,  with  con- 
centric markings  and  a  nipple  in  the  center,  which  is  usually 
darker  in  color  than  the  surrounding  portion  of  the  shell.  The 
winter  is  passed  in  a  half-grown  condition,  and  there  are  no 
eggs.  The  breeding  season  begins  soon  after  June  20  and  ends 
about  December  1  in  Connecticut,  three  or  four  broods  appear- 
ing in  a  season.  For  a  full  account  of  its  life  history  and 
spread,  see  Bulletin  No.  135  of  this  Station. 

This  scale  is  the  worst  pest  of  the  fruit  grower  in  Connecticut, 
and  attacks  all  kinds  of  fruit  trees,  except  the  sour  cherry 
{Primus  cerasus) ,  and  many  kinds  of  shade  trees  and  ornamental 
shrubs  are  attacked  and  sometimes  killed.  A  list  of  trees  and 
plants,  showing  their  susceptibility  to  attack  by  this  scale,  was 
published  in  the  Report  of  this  Station  for  1902,  page  130.  A 
thorough  spraying  in  the  fall  after  the  leaves  drop,  or  in  the 
spring  just  before  the  buds  start,  using  a  lime  and  sulphur  mix- 
ture, seems  to  be  the  best  remedy  for  Connecticut.  This  mixture 
is  usually  prepared  by  boiling  together  20  pounds  quicklime  and 
14  pounds  sulphur  for  45  to  60  minutes  in  enough  water  to  keep 
it  a  liquid.  After  boiling,  water  should  be  added  to  make  40 
gallons,  and  the  whole  applied  at  once.  Satisfactory  mixtures 
can  be  made  without  boiling  by  using  potassium  or  sodium  sul- 
phide, caustic  soda  or  sal  soda  to  aid  in  dissolving  the  sulphur. 
Some  of  these  mixtures  and  the  proper  outfit  for  spraying  are 


14  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    151. 

described  in  Bulletin  No.  146,  and  reproduced  in  the  Report  of 

this  Station  for  1904,  pages  240-252. 

The  accompanying"  illustration  of  the  San  Jose  scale  ( Fig- 
ure   14)    will    serve    to 
■  1  ji^      show  the  appearance  of 

the  other  kinds  which  so 
closely  resemble  it.  All 
can  be  combatted  in  the 
same  way,  viz:  by  spray- 
ing the  dormant  orchard 
trees  with  the  lime  and 
sulphur  mixture,  and  by 

fumigating  nursery  stock  with  hydrocyanic  acid  gas. 


Fig.  14. 


San  Jose  scale  on  peach  twij 
Twice  natural  size. 


24.  ELM  ASIPIDIOTTJS—Aspidiotus  ulmi  Johns.' 

This  is  a  small  circular  scale  resembling  the  preceding,  which 
is  found  on  the  smooth  or  inner  bark  in  the  crevices  of  the 
rough  bark  of  the  trunks  and  larger  branches  of  elm  trees.  It 
seems  to  do  very  little  damage,  but  may  be  found  on  most  of 
the  elm  trees  of  New  Haven,  and  doubtless  occurs  throughout 
the  state. 

25.  CIRCULAR  SCALE :   FIG  SCALE— Chrysomphalus  aonidum 
Linn   (ficus  Ash.). 


Fig.   15.     Circular  or  fig  scale  on  rubber  plant. 

Rubber  plant,  orange,  palms,  camellias  and  oleander  in 
greenhouses  are  often  infested  by  a  round  dark-colored  scale 
which  stands  out  prominently  from  the  surface  of  the  leaves. 


ARMORED    SCALES.  I  5 

In  fact  it  is  almost  conical  in  shape,  reddish  brown  or  nearly 
black,  with  an  orange  apex,  and  is  shown  in  Figure  15.  Pre- 
sumably it  continues  to  breed  throughout  the  year  under  glass, 
and  continued  spraying  is  necessary  to  keep  it  in  check. 

26.  MORGAN'S  SCALE  —  Chrysomphalus  dictyospermi  Morg. 

This  species  is  a  serious  pest  of  palms  at  Pierson's  large  com- 
mercial greenhouses,  Cromwell,  and  it  has  also  been  taken  in 
private  plant  houses  in  other  parts  of  the  state.  It  is  of  about 
the  same  color  as  the  preceding  species,  but  is  flatter,  and  pro- 
jects only  slightly  from  the  leaf.  Mr.  H.  E.  Hodgkiss  studied 
this  scale  at  the  Massachusetts  Agricultural  College,  and  found 
that  several  generations  are  produced  each  year,  but  these  over- 
lap so  as  to  become  indistinct.  The  females  bring  forth  living 
young,  are  parthenogenetic,  and  males  are  unknown.  Fumi- 
gating the  house  with  hydrocyanic  acid  gas,  using  7.5  grams 
potassium  cyanide  for  each  100  cubic  feet  of  space,  for  forty 
minutes,  after  dark,  with  the  plants  free  from  moisture,  is  the 
treatment  advised  by  Mr.  Hodgkiss  after  making  many  experi- 
ments. It  is  probably  a  safe  remedy  for  nearly  all  of  the 
greenhouse  scales. 

27.  OYSTER  SHELL  SCALE— Lepidosaphes  uhni  Linn 
(formerly  Mytilaspis  pomorum  Bouche). 

One  of  the  most  common  and  widely  distributed  of  all 
coccids.  It  is  a  pest  of  fruit  trees,  especially  apple,  and  many 
young  sprouts  and  seedlings  of  birch,  poplar,  willow,  ash  and 
butternut  are  killed  by  it  each  year.  Lilac  is  also  infested. 
There  is  but  one  brood  annually, 
and  the  insect  winters  in  the  form 
of  oval  white  eggs  under  the  female 
shells.  The  eggs  hatch  in  Connec- 
ticut about  the  first  of  June,  the 
young,  crawl  for  a  few  hours,  then 
settle  upon  the  bark  and  form 
shells,  becoming  mature  in  Septem-      FlG-  l6-    °3'ste[ she11  scale 

'  &  on  poplar. 

ber.     Eggs  are  laid  about  the  first 

of  October,  and  the  females  die.  The  female  scale  (or  shell), 
is  from  2  to  3  mm  long,  about  the  same  color  as  the  bark  upon 
which  it  rests,  elongated  pyriform  in  shape,  and  more  or  less 
curved.      It  is   shown  in   Figure    16.      Male   shells   are  much 


1 6  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    1 51. 

smaller  and  less  curved  than  those  of  the  female.  The  adult 
male  has  two  wings,  and  is  seldom  seen.  Spraying  with  kero- 
sene emulsion  or  soap  and  water  soon  after  the  eggs  hatch  will 
hold  this  scale  in  check.  For  a  more  complete  account  see 
Bulleton  143,  or  the  Report  of  this  Station  for  1903,  page  229. 

28.  THREAD  SCALE — Ischnaspis  longirostris  Sign. 

This  is  a  long  narrow  black  scale  attacking  palms,  pandanus 
and  many  other  plants  in  greenhouses.  It  has  been  taken  in 
Connecticut  only  at  one  greenhouse  in  New  Haven,  where  it 


Fig.   17.     Thread  scale  on  palm  leaf. 

was  quite  abundant.  Little  is  known  of  its  life  history,  and  the 
male  is  unknown.  The  female  shell  is  from  2  to  3  mm  long, 
and  about  eight  times  as  long  as  broad,  and  more  or  less 
curved.  (See  Figure  17.)  The  writer  has  had  no  experience 
in  combating  this  scale,  but  the  same  treatment  used  for  other 
greenhouse  scales  will  doubtless  hold  it  in  check. 

29.  CHAFF  SCALE — Parlatoria  pergandii  Comstock. 

This  is  common  on  various  greenhouse  plants,  especially 
orange  and  lemon.  It  is  oval  in  shape,  with  the  molted  skin  at 
one  end,  and  is  light  yellow  in  color.  It  is  usually  found  in 
clusters.  The  common  sprays  used  for  greenhouse  scales  seem 
to  be  effective  against  this  species. 


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